The Hunt for I‑16: How One Submarine Hunt Changed the Course of World War II

 In ASEAN, C4ISR, GDI, Defense, Air

Admiral Soemu Toyoda needed answers. The newly appoint­ed com­man­der in chief of Japan’s Combined Fleet, Toyoda found him­self facing sev­er­al unpleas­ant facts. By May 1944, Allied naval and air strength in the Pacific Ocean was grow­ing at an alarm­ing rate. Already, fast-moving enemy forces had advanced far across north­ern New Guinea and into the Admiralties and through the Marshall Islands in the Central Pacific.

Toyoda could not yet deter­mine whether the next American thrust would head north into the Marianas or con­tin­ue west toward Palau and the Philippines. The six car­ri­ers, 10 bat­tle­ships, and 40 other war­ships of his First Mobile Fleet could crush an enemy advance, but those ves­sels car­ried only enough fuel for one deci­sive sea cam­paign. Before send­ing Japan’s last remain­ing sur­face force into battle, Toyoda required hard evi­dence of American naval activ­i­ty and inten­tions.

Much had changed since the heady days of 1941 and early 1942. Japanese long-range patrol air­craft, once able to roam far into Allied ter­ri­to­ry, could now only rarely pen­e­trate the enemy’s air defense umbrel­la. Radio inter­cep­tion, so useful during the war’s first months, was ren­dered vir­tu­al­ly use­less by advanced American com­mu­ni­ca­tions secu­ri­ty pro­ce­dures. That left sub­marines as Toyoda’s sole reli­able means of recon­nais­sance.

Unfortunately, Japan’s largest, most capa­ble fleet subs — the ocean­go­ing I‑class boats — were increas­ing­ly being pressed into ser­vice as trans­ports haul­ing food and sup­plies to Imperial Japanese Army gar­risons marooned by leapfrog­ging Allied forces. Scouting duties would have to be per­formed by the small­er Ro-class sub­mersibles of Rear Admiral Noboru Owada’s Submarine Squadron Seven. These ves­sels were designed for coastal patrol, how­ev­er, and lacked the sur­face radar sys­tems Owada deemed so nec­es­sary for con­duct­ing recon­nais­sance mis­sions.

What their crews did not lack was courage. Each Ro-class boat then anchored at Saipan in the Marianas held between 40 and 60 sailors, the cream of the Imperial Japanese Navy under­sea force. Combat vet­er­ans all, these well-trained seamen posed a sub­stan­tial threat to any Allied vessel caught in their periscope sights.

Yet Owada’s orders were to locate and report enemy war­ships not sink them. He direct­ed his boats to picket a 200-mile track between New Guinea and the Caroline Islands labeled the NA Line. Should they spot an Allied armada steam­ing toward the Philippines, these scouts were sure to radio back with pos­i­tive con­fir­ma­tion. Armed with this intel­li­gence, Admiral Toyoda could then order his Combined Fleet into the cli­mac­tic battle he believed would win vic­to­ry for Japan.

On May 15, 1944, the seven Ro-class boats of Submarine Squadron Seven depart­ed Saipan to take up sta­tions along the NA Line. Their 650-mile voyage would take six days and was tracked close­ly both by Owada’s staff on Saipan and Combined Fleet head­quar­ters in Japan.

The progress of Squadron Seven was fol­lowed by anoth­er group of naval offi­cers, lis­ten­ing from a heav­i­ly guard­ed facil­i­ty at the American naval base at Pearl Harbor, Hawaii. These men belonged to Fleet Radio Unit-Pacific (FRUPac), the top-secret signal intel­li­gence center respon­si­ble for col­lect­ing and decod­ing all enemy radio com­mu­ni­ca­tions inter­cept­ed by the U.S. Navy. Already FRUPac had helped win a stun­ning American vic­to­ry at Midway, not to men­tion its role in Operation Vengeance, the ambush of Admiral Isoroku Yamamoto by U.S. Army Air Forces Lockheed P‑38 Lightning fight­ers in 1943. This bril­liant team of math­e­mati­cians, puzzle solvers, Japanese lin­guists, and elec­tron­ics experts was about to change his­to­ry once again.

A rou­tine radio trans­mis­sion, made on May 13, 1944, set in motion what would become one of the most epic bat­tles in the annals of anti­sub­ma­rine war­fare. This short, encrypt­ed mes­sage came from Lt. Cmdr. Yoshitaka Takeuchi, cap­tain of the fleet sub I‑16.  Takeuchi’s report, plucked from the air­waves by American tech­ni­cians, advised Admiral Owada that his vessel was due to arrive with food and sup­plies for the bypassed gar­ri­son at Buin on the south­west tip of the island of Bougainville on May 20.

FRUPac ana­lysts deci­phered enough of Takeuchi’s dis­patch to esti­mate his course and time of arrival at Buin. This infor­ma­tion quick­ly made its way to Admiral William F. “Bull” Halsey’s Third Fleet head­quar­ters, also at Pearl Harbor, for action. Halsey had to move fast, though, since intel­li­gence such as this was extreme­ly per­ish­able. Countless fac­tors from weath­er to mechan­i­cal break­downs to unpre­dictable sea con­di­tions might put I‑16 miles from where the Americans thought it was. And just because FRUPac knew the where­abouts of an enemy sub did not mean the U.S. Navy could get hunter-killer teams there quick­ly enough to find and sink it.

Fortunately for the Allies, a small group of destroy­er escorts (DEs), pur­pose-built to attack sub­marines, was then await­ing orders at Purvis Bay off Florida Island in the lower Solomons. The group, des­ig­nat­ed Escort Division 39, con­sist­ed of USS England (DE-635), USS George (DE-697), and USS Raby (DE-698), all newly com­mis­sioned Buckley-class ves­sels on their first war cruise. Kept busy thus far with rou­tine convoy escort duties, few sailors aboard these three DEs had yet seen combat.

A series of events would rapid­ly trans­form them into sea­soned vet­er­ans. On May 18, a com­mu­niqué from Third Fleet arrived direct­ing Escort Division 39 to inter­cept a “Japanese sub believed head­ing to supply belea­guered forces at Buin.” After post­ing its esti­mat­ed loca­tion, the elec­tri­fy­ing mes­sage con­clud­ed: “He is believed to be approach­ing this point from the north and should arrive in that area by about 1400 [hours] 20 May. Good hunt­ing.”

Each of the three DEs in Escort Division 39 mea­sured 306 feet in length with a beam of 36 feet. Fully combat loaded, a Buckley-class destroy­er escort dis­placed 1,740 tons. Two General Electric turbo-elec­tric engines drove the vessel to a top speed of 24 knots, while max­i­mum cruis­ing range exceed­ed 5,000 miles. A ship’s com­pa­ny typ­i­cal­ly includ­ed 15 offi­cers and 198 enlist­ed men.

A suite of elec­tron­ic sen­sors assist­ed the crew in its mis­sion of locat­ing enemy tar­gets. SL search radar helped find sur­face ves­sels, while SA “bed­spring” radar iden­ti­fied pos­si­ble aerial threats. But the DE’s pri­ma­ry detec­tion system was QSL‑1 sonar, which sent a pulse of high-inten­si­ty sound called a “ping” into the water. Echoes reflect­ed off such solid objects as a sub­ma­rine returned to the ship, where trained sound oper­a­tors could then deter­mine the contact’s range and bear­ing.

The destroy­er escort also packed a lethal punch. Apart from 20mm Oerlikon and quad-mount­ed 1.1‑inch anti­air­craft can­nons, each Buckley-class DE came equipped with three Mk 22 3‑inch/50-cal­iber deck guns — two for­ward and one aft. Three 21-inch tor­pe­does in a triple tube launch­er mount­ed atop the super­struc­ture deck were intend­ed for sur­face ves­sels, while a bat­tery of depth charge pro­jec­tors on the ship’s fan­tail could dev­as­tate plung­ing sub­marines with a string of “ash­cans” each con­tain­ing up to 600 pounds of high-explo­sive filler.

Just enter­ing ser­vice in the Pacific that spring was a new and deadly weapon, the Mk 10 “Hedgehog” for­ward-firing spigot mortar. The DEs of Escort Division 39 all car­ried this British-designed pro­jec­tor, which fired a salvo of two dozen 24-pound con­tact-fused charges intend­ed to fall in a cir­cu­lar pat­tern up to 270 yards ahead of the ship. Hedgehog rounds could be aimed to fall slight­ly right or left of center line and would only explode if they struck a sub­ma­rine. By 1944, Japanese sub­ma­rine cap­tains had learned how to evade blind­ly dropped depth charges; Hedgehog-equipped destroy­er escorts could now track a target on sonar through­out their attack and thus great­ly increase the chance of a pre­ci­sion kill.

Sub hunt­ing was a com­pli­cat­ed, intri­cate task that required every offi­cer, NCO, and blue­jack­et — from sound­men to Hedgehog gun­ners to the engine room gang — to work togeth­er as a team. Even the newest hands in Escort Division 39 knew their only chance to defeat the foe was through relent­less train­ing, and aboard one of those DEs train­ing had become an obses­sion.

Since its com­mis­sion­ing in December 1943, the USS England, named for Ensign John Charles England, killed at Pearl Harbor, had earned the rep­u­ta­tion of being a “taut ship.” Her crew­men devot­ed them­selves to achiev­ing excel­lence in equip­ment main­te­nance, ship han­dling and, above all, pro­fi­cien­cy with the vessel’s weapons sys­tems. They knew theirs was a kill-or-be-killed pro­fes­sion; coming in second against a Japanese sub­ma­rine meant vio­lent death on the lonely ocean.

Leading the England’s com­pa­ny to excel­lence was an unlike­ly taskmas­ter. Lieutenant John A. Williamson, a 26-year-old from Birmingham, Alabama, served as the ship’s exec­u­tive offi­cer (XO). Taking a reserve officer’s com­mis­sion in 1940, Williamson soon found him­self aboard the destroy­er USS Livermore in the North Atlantic. Although the United States was then tech­ni­cal­ly not at war, fully armed American war­ships on the “Neutrality Patrol” reg­u­lar­ly shep­herd­ed con­voys to and from Great Britain during the height of the U‑boat peril. During his nine months of escort work, Williamson often wit­nessed first­hand the hor­rif­ic toll that German subs were taking on Allied mer­chant­men.

Lieutenant Williamson next served as an instruc­tor at the Subchaser School in Miami, where he helped train the Navy’s next gen­er­a­tion of sonar oper­a­tors. He then skip­pered a wooden-hulled patrol craft along the East Coast before receiv­ing orders to join England for duty in Pacific waters. As XO, Williamson brought to his new ship a remark­able com­bi­na­tion of battle expe­ri­ence, tech­ni­cal knowl­edge, and pas­sion for excel­lence.

Source: National Interest

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